I was reading Finding originating account of anonymous posts and I wanted to chime in but found that it was locked.
I think many people assume that users want to become anonymous to hide from both admins and other users, but in our community some users desire to become anonymous only to hide from other users, not admins. Many, quite possibly most, people are extremely shy about revealing ignorance, and so they won’t post questions of a certain type if people know who they are. What this does is drastically shrink the effective “active” size of a community. It’s not noticeable in huge internet-scale communities, but it can make a small community completely non-viable. So for communities like this, making it easy for admins to identify anonymous posters can be very helpful – and is not a violation of privacy as long as the correct language is used around enabling the anonymizing feature.